Sound amplifier



Jan, 22 1924.

A. A. THOMAS SOUND AMPLIFIER Filed Nov. 16

MM/Y//ML/ ff f6 @a mnu I5 Sheets-Sheet 2 r/mmml gvwamt'oa A. THOMAS oUND AMPLIFIER Filed Nov. 16

Jan. 22 1924.

A. A. THOMAS SOUND AMPLIFIER Filed Nov. 16, 1922 3 Sheets-Sheet 5 Snowdon m Jan. 22 1924.

Patented lan. 22, 1924.

ADLPH A. THOMAS, 0F NEW YORK, N. Y.

SOUND' AMrLIFIEn.

Application led November 16, 1922. Serial No. 601,237.

' To all whom t may concer/n.:

'ment to control the the yamplified sound Be it known thatv I, ADoLPH A. THOMAS, a citizen of the United States, and a resident of the city of New York, county and,

State of New York, have invented new and useful Improvements in Sound Amplifiers, of which the following is a specification.

My invention relates to acoustic devices for amplifying sounds produced by vibratory diaphragms, as in phonographs, telephone receivers, radio receiving apparatus, and the like. The object ofA my invention is to produce a sound-amplifier giving improved tone effects and capable of adjustquality ,and volume of The most common form of sound-ampliier in use is a horn or megaphone. In fact, this type of amplifier is employed almost universally in phonographs'and radio loudspeakers. Everybody familiar with amplifying horns knows that they possess certain inherent objections in reference toA tone quality. These objections arebest described' by saying that horns give out sounds of an unnatural horny quality with consequent loss in clea-rness. In an endeavor to reduce this defect as much as possible, manufacturers have put in the market a great variety of shapes and sizes of horns constructed of various kinds of materials.

It is known that metal horns produce hard penetrating sounds, which may become particularly offensive in the higher tones, especially when 'the vibrations of the diaphragm are of considerable amplitude. This is a common experience. So that, while the tones of a metalvhorn have volume, they are defective in quality and distinctness.

On the other hand, horns of non-metallic material-such as wood, liber, compressed paper, composition, and the like-produce sounds of considerably less volume than corresponding horns ofmetal. While these softer tones may be preferable to the loud sounds of a metal horn when the vibrations of the dia hragm are strong, there is theobjection 't at a non-metallic horn has lit-I tle carrying power when the diaphragm vibrations are weak.

Attempts have heretofore` been made to damp or weaken the action of phonograph A horns by choking back the sounds. This has been done either by "partially closing the mouth of the horn or by using a damper in the throat of the horn. In either case, the

resultant tones are decidedly muiiled or choky and lack the required clearness.

The foregoing and other objections and disadvantages of prior sound-amplifiers are eii'ectively overcome by the new amplifying device of my invention.. Broadlystated,

the fundamental idea of my invention involves the use of a plurality of sound chambers constructed to produce different' tone effects, so that the resultant tones are a v blending of the sounds produced by the individual amplifying chambers. By combining a relatively' resonant chamber with a ,relatively mellow chamber, I 4secure a resultant tone effect which embodies the acoustic advantages of -both chambers. I also provide means for controlling the resultant reproduction of the amplifier by varying the -acoustic'eii'ect of onel or more of the sound chambers. j

One of the simplest forms of my invention comprises a metal horn surrounded by non-metallic Walls (say, of wood) so arranged as to form a conical or pyramidal phragm of a radio loudspeaker. By means of properly arranged openings, the sound l waves enter both amplifying chambers. The result-ant tone effect of the two chambers is a blnding of the sharp resonant tones of the inner metal horn with the mellow tones of the outer wooden chamber. In other words, I may say that the resonant tones of the horn are mellowed by the tones of the surrounding outer chamber, and the mellow tones of this chamber are strengthened by the resonant tones of the horn.. My new amplilier thus combines volume with quality.

To vary the resultant tone effect of the instrument as desired, I provide means' for readily controlling the relative proportion of sound waves issuing out of each chamber. For this purpose I employ a valveor shutter arrangement by means of which the travel of sound, waves through each chamber is regulated. Assuming, as in the example above cited, that we have "an inner metal chamber and an outer .Wooden chamber, the more sound waves we send through the metal chamber, the stronger becomes Ui? mi the nal reproduction. Conversely, the greater the proportion of sound waves that pass through the outer wooden chamber, the more mellow are the resultant tones. This control of the sound-amplifying action of my new apparatus is especially useful in phonographs and radio loudspeakers.

Another feature of my invention resides in the construction whereby the inner horn or chamber is provided with a sound-conveying tube which is bent back over the horn, thereby producing an amplifier of compact dimensions and yet providing a sound passage of increased length, with a resultant increase'in the volume of tone production.

ln order to explain my invention fully and clearly, l shall describe in deft-ail the illustrative embodiments shown in the accoman inof drawin s in which- Figure 1 is a longitudinal cross-section of box or cabinet containing my new ampli- Fig. 2 is a front view of the box shown in Fig. 1; ig. 3 is a view similar to Fig. 2, with the front grille or frame removed;

Fig. 4 is a detached view of the cast-ing to which the inner ends' of the sound chambers are connected;

Fig. 5 is an enlarged cross-sectional view of the casting;

Fig. 6 shows my new amplifier attached to a radio loudspeaker, the amplifier and a portion of the loudspeaker being shown in crosssection;

Fig. 7 is a cross-sectional view of a phonograph provided with the amplifier of my invention;

Fig. 8 is a view in longitudinal cross-section showing a modified form of amplifier, portions of the horns being broken away;

Fig. 9 is a View taken approximately on line 9 9 of Fig. 8;

Fig. 10 shows a full view, on a smaller scale, of the amplifier shown partially in Fig. 8, the walls of the horns being broken away for clearness; A v

Fig. 11 is a cross-sectional view showing a modified form of control valve .for the surrounding outer chamber R. This lateral sound chambers; Y

Fig. 12 is a cross-section approximately on line 12--12 of Fig. 11; and

Fig. 13 is a cross-section approximately on line 13--13 of Fig. 11, except that the valve is shown turned to close the outer casting indicated as a whole by C, which may conveniently be cast of metal or molded out of some suitable composition material. When l' speak of the part C as a casting, lf

luse the term as a convenience in a broad sense, irrespective of the process of which lastest the part is made or the material of which it slots 3 permit adjustment of the height of the casting. Any suitable supporting means for holding the casting C in proper position may be used. Casting C is formed with a tubular hub having a Afront section 5 and rear section 6, this hub 'providing a sound passage Hub section 5 issurrounded by an outwardly diverging flange 8. In the drawings, this flange is shown rectangular, because it has been assumed that the walls of the outer sound chamber secured to this flange are four in number, as will presently be explained. The shape of the flange 8 will depend on the shape of the inner end of the sound chamber to be attached to it.

Un the hub section 5 of casting C is mounted the inner end of a horn, indicated as a whole by H. The outer surface of hub section 5 maybe slightly tapering, so as to make it easy to slip the horn on the casting `in a tight tit, as indicated in Figs. 1 and 5.

Horn H is surrounded by a sound chamber which, in this instance, is formed by four walls 9 secured at their inner ends to ange 8` of casting C. Suitable fastening devices, such as screws or bolts 10, pass through holes 11 in flange 8 into the walls 9. The chamber formed by walls 9 is indicated as a whole by R.

VThe horn or inner chamber H is preferably constructed of a material adapted to give a strong resonant reproduction-such as brass, aluminum, German silver, or other material suitable for this purpose. The walls 9 of the outer sound chamber are preferably of non-metallic material adaptedto give a mellow reproduction-such as wood,

ber or a suitable composition. lf wood is used, maple gives particularly good results.

As seen in Figs. 1 and 3,- horn H is provided with openings 12 for permitting the passage of sound waves laterally into the expansion of the sound waves from the inner to the outer chamber, before reaching the air, improves the quality of the final tone reproduction. The size, arrangement and number of openings 12 may be varied, and

will depend upon the size, shape and materials of the sound chambers and also upon the particular acoustic effects desired.

Above the sound chambers in the box or cabinet A is a sound-conveying tube or arm 13, which is preferably tapering, as shown in Fig. 1. The outer smaller end 14 of this arm terminates at the top of the box and is adapted to receive a suitable telephone receiver, indicated as a whole by T. This receiver may be of any approved type or construction, such as are used in radio reception, for instance. There are many sizes and styles of such receivers on the market. The inner end of tone arm 13 is connected with the sound passage 7 of casting C by a substantially U-shaped tube 15. .As shown in Fig. 1, the lower end of the U-shaped tube 15 is fitted into hub section 6 of'casting C. Sound tubes 13 and 15 are preferablyl of metal and, by arranging them as shown in Fig. 1, I secure a sound passage of great length between the telephone receiver T and the inner vend of horn H, the effect bein that of a horn having a portion turned bac upon itself. This increased length of horn increases its amplifying power and yet produces a compact construction, a feature particularly desirable in radio-receiving apparatus. 4

The front of box A is open and over this opening'is fastened a frame or grille F, as shown in Figs. 1 and 2. Grille F may be stamped or cut out of metallic or non-metallic material, or it may be molded out of a suitable composition substance. This grille, which is secured tothe box by any suitable means, such as screws 16, is provided with a central ring 17 adapted to fit over the mouth of horn H, as shown in Figs. 1 and 2. Withvin the ring 17 is a disk 18 having openings 19, of which there are four in number in the present instance. On disk 18 is supported a rotary disk 20, which has openings 21 similar in shape and arrangement to openings 19. The rotary disk 20 is held in place by'a spindle 22 provided on the outside'with a knob 23. B turning knob 23, the disk 2O may be move to cover or uncover the openings 19. In other words, the openings 19 and the disk 20 with its openings 21 constitute a valve or shutter for controlling the mouth of horn H.

It is clear that when the disk 20 is in fully closed position, all the sound waves entering the horn are compelled to pass through the lateral openings 12 into the outer chamber R, whence they issue into the free air. Asseen from Fig. 2, the grille F leaves the mouth of chamber R practically unobstructed, there being only the thin connecting strips 24, which support the ring 17. If the walls 9 are of wood or other suitable non-metallic material, the closing of valve disk 20 results in a mellow reproduction of tones passing through the amplifier: By opening valve disk 20 partially, the sound ,waves entering the horn pass into the outer air partly through the horn and partly through chamber R, thus giving a stronger reproduction than when the disk 20 is closed. The more we uncover the horn openings 19, the more sound waves travel directly through and out of the horn. 'ge greater the proportion of sound waves i ing out of the resonant horn H, the stronger and more resonant will be the final or resultant tone effect of the instrument. In this wa by blendin the resonant tones of horn with the me low tones of chamber R, we secure a tone reproduction which combines the advantage of volume of the inner resonant chamber with the advantage of mellowness of the louter chamber. The resultant tonal effect may be varied by changing the proportion of sound waves passing throu h each chamber.

In Fig. 6, I ave shown my new combination lof Sound'chambers attached'in an upright position to a radio loudspeaker, indicated as a whole by L. It will not be necessar to repeat the details of construction an assemblage of the parts shown in Fig. 6, since they are similar to those shown inY Fig. 1. It will be suiicient to say that in Fig. 6 I have employed the same reference characters as in ig, 1 to indicate correspondin parts, except that a prime mark is used wit the characters for the sake of distinction. I may point out that in Fig. 6 the wall or walls 9 of the outer sound chamber R are substantially conical in cross-scction instead of rectangular. Also, in Fig. 6, the casting C has an extension 6 fitting directly into the sound paage or tube 25 of loudspeaker L. The operation and control of the amplifier shown in Fig. 6 are the same as those of the construction previously described.

In Fig. 7, I have shown my invention embodied in a phonograph. Practically the only difference between the constructions shown in Figs. 1 and 7 is that in Fig. 7 there is a casting C2 which has atubular extension 26 for connecting the horns or sound chambers R2 and H2 with the usual tone arm 27. Casting C2 may be secured to the underside of motor board 28 by screws or bolts 29. Otherwise, what has been said about Fig. 1 applies fully to Fig. 7. advantages of my invention in a phonograph for controlling the reproduction are obvious. For instance, if the operator de'- sires a mellow reproduction of `a loud record, he need only turn the valve disk 2O to 115 close the mouth of the horn either completely or part way. On the other hand, in the lease of a soft record, the reproduction is strengthened by opening the horn and thereby securing the advantage of its resonance in combination of the softer quality of the outer chamber.

Instead of using a valve or shutter to control the mouth of the inner horn, I may mount a conical valve on grille F to lit closely against the horn and control the openings 12. As this modification is easily understood, I need not illustrate and describe itfin detail, particularly since I do not claim it specifically. mention it mere- 13 its inner end provided with sound passages 37. A horn 38 is mounted at its inner end on the hub 35 of casting 30, and is thus surrounded by the outer horn 32. The sound passages 36 lead into outer horn 32 and the sound passages 37 lead into the inner horn 38. The relative shapes and sizes of horns i 32 and 38 are such that the sound space or chamber S between the two horns is of sufficient area to permit the free passage of sound waves.

To the casting 30 is secured a suitable eX- tension 39 by means of which the inner chamber 4() of the casting is connected to a source of sound, which may be the vihratory diaphragm of a. telephone receiver, or a phonograph sound box, or a radio loudspeaker. l I will now describe the means by which the passage of soundwaves into horns 32 and 38 is readily controlled to produce different tone eil'ects. Within the chamber 40 of casting 30 is mounted a valve, indicated as a whole by V. This valve consists of a disk 4I and a tubular extension 42. Valve disk 41 has openings 43 similar in size and arrangement to the passages 36. In Fig. 9, the disk 4l is in position to cover the passages 36 completely, which are therefore indicated in dotted lines. The cylindrical valve portion 42 is at its inner end providedwith openings 44, which are substantially-similar in size and arrangement to the sound passages 37. In Figs. 8 and 9, the valve openings 44 are shown in register with the sound passages 37. so that all of the sound waves entering chamber pass into the inner horn 38. The controlling valve V is operated from the outsideby any suitable means, such as a handle or lever 45, which proects through a slot 46 in the casting. If desired,

f pins or screws 47, or other means, mayA be used for positively holding the valve V against axial movement, although the lever 445h will probably be suilicient for that purpose` Let us suppose that the inner horn 38 is constructed of a material adapted to give a resonant reproduction, and that the outer horn 32 is of a material which gives a relatively softer or more mellow reproduction. After the handle is moved into the position shown in Figs. 8, 9 and 10 to close the sound assages 36 completely and to open fully t e sound passages 37, all the sound waves entering the amplifier pass through the resonant horn 38 and we get a correspondingly loud and sharp reproduction. In Fi 10 this position of the contrplling valve is indicated as the loud position. By movving the handle 45 half-way to the rightl (as viewed in Fig. 9), `the sound passages 36 and 37 are approximately half-way open and the sound waves enteringthe amplier ass into the free air partly'through the me low outer horn 32 and partly through the resonant inner horn 38. The resultant tone effect is a blending of the acoustic laction of the `two horns and gives a more mellow repro- Figs. 1l, 12 andl3 show a. construction similar to Figs. 8, 9 and 10, except that the controlling valve is slightly different in form, although it is precisely the same in operation as the previously described valve V. Referring in detail to the last three figures, we have a suitable casting 48 carrying yan outer horn 49 and an inner horn 50, which are secured to the casting in the same way as the horns previously referred to. One of these horns (say, for example, the outer horn 49) is constructed of amaterial adapted to give a comparatively mellow reproduction, and the other horn (in that case horn 50) is of a material which gives a more resonant reproduction. The casting 48 has a cylindrical hub 51 provided with a set of sound passages 52Y and another set of sound passages 53. As seen from Fig. 11,'the sound passages 52 lead into the outer horn 49 and the sound passages 53 communicate with the inner horn 50. Within the hub 51 is mounted a cylindrical valve V having a set of openings 54 and another set of openings 55. Valve openings 54 are adapted to' control the sound passages 52, and valve openings 55 are arranged to control the vsound passages 53. The valve V is controlled from the outside by any suitable means, such as a handle 56, which ro'ects through a slot 57 in the casting 48. lh igs. 1l and 12, the valve V is in position to close the sound openings 53 and open the sound openings 52, so that all the sound waves pass through the outer horn 49, which we have assumed to he the more mellow sound chamher. The valve is thus in what we may call the sott position, as indicated in Fig. 12.

ll-l

By throwing the handle 56 over into the loud7 position, the outer horn is closed and the inner horn is fully opened to the sound waves, with the result that we get a stronger reproduction.

LIn Figs. 10 and 11, the inner horns 38 and and 50 may, if desired, be provided with lateral openings similar to the innerhorns shown in Fig. l, 6 and 7. In that case, the sound waves would always issue out of both horns, but valve V or V the same to control the of sound waves passing It is clear that the amplifiers shown in Figs. 8 to 13, inclusive, may be used in radio loudspeakers by simply inserting them in the base of the instrument, as in Fig. 6, or they may be embodied in phonograph cabinets similar to the arrangement shown in Fig. 7. In the latter case, the tone-controlling valve could be operated from the side of the cabinet bysimply attaching a rod to the end of handle 45 or 56, as will be readily understood. Also, it is apparent that the constructions of Figs. 8-13 may be enclosed in a box like that shown in Fig. 1. In that case, the extension 39 (Fig.`8) or 48 (Fig. 11) is connected to the arm 15 of F ig. l.

Attention iscalled to the fact ythat the tone-controlling device of my invention, whether employed at the mouth of the inner horn (as in Figs. 1, 6 and 7), or at the base of the horns (as shown in F igs. 8 to 13), is not a choking or throttling damper; rather is it a valve for shifting or deflecting the passage of sound waves through both horns simultaneously in varying proportions. Consequently, my controlling mechanism doesnot produce the choky effect of the horn dampers previously employed.

It will be apparent from the foregoing explanation that my new sound-amplifier with its soundl chambers of dilferent tone effects gives better reproduction than prior devices employing a single horn or chamber. Furthermore, by means of the tone valve or shutter, the amplifying action of my device is readily controlled by t-he oprelative proportion through the horns.

verator to produce any tone effect within the limits of the instrument. In the matter of construction, my new amplifier is remarkably simple and easy to make, besidesvbeing compact in the arrangement of parts.

The amplifier of my invention possesses special advantages for radio reception, where broadcast programs vary from the reporting of sporting events to the'rendition of vocal or instrumental solos. An amplifier adapted to give the best reproduction of speech does not usually give the best results in reprodrucing music or song, and vice versa. For instance, it has been found that in reproducing announcements of sporting events in a large hall, a loudspeaker with a would operate just high resonant pitch is more satisfactory than one emitting low rumbling tones, which lack clearness. On the other hand, a piano solo is best reproduced with an amplifier having mellow tonal characteristics. Now, my new amplifier may be so regulated in its tonereproduction as to give the best results in the reproduction ,of any kind of broadcasting. In other words, the amplifier of my invention embodies a plurality of amplifiers in a single instrument.

Although I have herein shown andvdescribed certain specific constructions, it is clear that the broad idea of my invention may be mechanically embodied in other Ways. The size, shape and material of the horns or sound chambers may be varied in accordance with the particular tone effects desired to be produced. Also, the number and relative arrangement of the horns may be varied to suit particular circumstances or to effect certain results. While I have spoken of the inner horns as the resonant sound chambers and of the outer horns as the more mellow sound chambers, it is obvious that the outer horns may be constructed to give more Areasonance than the inner horns. The difference in tone effects between the various sound chambers may be lbrought about not only by the use of different materials, as already mentioned, but by variations in siz'e and shape of the horns, even with the same material. Nor is it necessary that the horns are nested, as shown, although that arrangement is desirablefrom a practical standpoint on account of the resulting compactness. When I refer to nested horns or sound chambers in the description and claims, I do not mean that they shall bel concentrically mounted, but I include any arrangement in which the smaller chamber is within the casing of the larger chamber.' In the broader aspect of my invention, the inner horn may be regarded as a wall Within the casing formed by the walls of the larger chamber and dividing said casing into two sound chambers of different tonal characteristics. It is preferable to support the horns independ-v ently of each other, for any direct connection between the horns, such as spacing rods, would cause the vibrations of one horn to/ be communicated to the other, thereby injuring the'quality of reproduction. The walls of the sound chambers should be smooth and rigid for the best results.`

, As far as I am aware, I am the first to plurality of sound chambers constructed lto produce different tone effects, and having` means for controlling th@ resultant tone quality by regulating the relative proportion of sound waves passing simultaneously through ,the amplifying chambers. I, there-l fore, claim this idea` inl a fundamental way. Since in the appended Claims I claim my dll.

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invention broadly and also specifically claim the construction of Figs. 1-5, I do tion, the inner chamber having sound openings `itor laterally communicating with the outer chamber, and means for controlling the relative proportion of sound waves passing through said openings;

2. A sound-amplifier comprising a plurality of nested sound chambers constructed to produce different tone eli'ects, and means for simultaneously controlling the acoustic effects of the individual chambers, whereby the'v resultant sound reproduction combines the tonal' characteristicstof said chambers in varying degrees.

3. A sound-amplifier comprising a pair of nested diverging sound chambers, the Walls of the inner chamber being of metal and the walls of the surrounding outer chamber being of non-metallic material, and means `for controllin the relative propor tion of sound waves lssuing simultaneously out of said chambers.

4c. In a sound-amplifier, a pair of nested diverging 'sound chambers open to the air at their `outer ends, the walls ofthe inner chamber beingof a material adapted 'to give a resonant reproduction, the walls of the surrounding outer chamber being of a` material adapted to give a relatively softer or more mellow re reduction, means for connecting said cham rs with a source of sound, and

van adjustable valve for controlling the relative proportion `of sound waves issulng simultaneously out of said chambers.

5. In a so'und-amplifier, the combination of a horn adapted to be connected at its inner end with a source of sound and constructed of a material adapted to give a resonant reproduction, outwardly diverging walls surroundin said horn and arranged to form around t e same a sound chamber open at its outer end, said walls being of a material adapted to give a relatively softer or more mellow reproduction, sound pas-` sages leading into saidv surrounding chamber, and means for controlling'said passages to vary the relative proportion of sqiund waves issuing simultaneously out of said horn andA out of said chamber.

6. In a sound-amplifier, a pair of nested diverging sound chambers open to the air at their louter ends 'and constructedv to yproduce different tone effects, means for connecting said chambers with a source of sound, and a valve for controlling the relative proportion of sound waves passing simultaneously through said chambers.

7. In a sound-amplifier, a casting comprising a main tubular section provided between its ends with a surrounding iange, one end of said tubular section being adapted to be connected with a source of. sound, a horn having its inner end fastened to the other end of said tubular section, diverging walls arranged to form a sound chamber around said horn and secured at their inner ends to said iange, the axis of said tubular section being substantially coincident with the axes of said horn and said surrounding chamber. 1

8. As a new article of manufacture for use in sound ampliliers, a casting comprising a of a horn open at its outer end and adaptedV to be connected at its inner end with a source of sound, outwardly diverging walls surrounding said horn and arranged to form around the same a sound chamber open at its outer end, said horn having sound openings for laterally communicating with saidv chamber, whereby the sound waves entering the horn pass into the outer air partly through the horn and partly through said surrounding chamber, and means for regu lating the relative proportion of sound waves issuing simultaneously out of said horn and out of said chamber.

l0. In a sound-amplifier, the` combination of a metal horn open at its outer end and adapted to be connected at its inner end with a source of sound, non-metallic walls surrounding said horn and arranged to form around the same a diverging sound chamber open at its outer end, said horn having sound openings for laterally communicating with said chamber, whereby the sound waves entering the horn pass into the outer air lpartly through the horn and partly throug surrounding chamber, and an adjustable shutter at the mouth of saidhorn for controlling the proportion of sound waves issuing out of the mouth of said. hor'n and out of said surrounding chamber.

11. In a sound-ampliiier, a pair of nested4 horns adapted to be connected with a source of sound, andan adjustable valve for controlling the relative proportion of' sound waves issuing simultaneously out of both horns. .a

ings for laterally communicatmg with the saidwim connected with a source of soun of a ro-` tatable valveor regulating the passage of sound lwaves simultaneou y through both horns 14. In a sound-amplifier, the combination --with a pair of nested horns ada ted to be connected with a source of soun of manually operable means for regulating the passage pli sound waves simultaneously vthrough both orns.

15. In a sound-amplifier, a pair of nestedhorns open at their outer ends and adapted to be connected with a source of sound, a frame at the mouth of the inner horn and having one or more sound openings and a rotary disk'mounted in said frame or controlling said openin to vary the relative pro ortion of soun waves issuing out of sai horns.

16. A sound-amplifier comprising a pair of nested diverging sound chambers open to the air at their front or outer ends, a soundconveying tube supported outside of said chambers and extendingvlen hwise thereof from near the front endsv o said chambers toward the inner ends thereof, the outer end of said tube being adapted to be connected with a sourceof sound, and a member for acoustically connecting therear or inner end or said tube with the inner end of said chambers. A

17. A sound-amplifier comprising, walls or partitions arranged to form a diverging sound chamber open to the air, a substantially U-shaped sound-conveying member arran ed partly within said chamber and partly without, said member tapering from its smaller sound-inlet end to its larger sound-outlet end, the mouth or larger end of said member terminating at or near the mouth of said chamber, and means for emitting sound waves from said member into said sound chamber. I

18. A sound-amplifier comprisingl walls arranged to form a diverging sound c `amber open at its front or larger end, ahorn supported lengthwise within said chamber, a

sound conduit at the inner ends of said horn. and chamber, and a sound-conveying tube mounted. outside of said chamber so as to extend from the front toward the rear thereof, the outer end of said tube being adapted to be connected with a source of sound fand the inner end of said tube being connected to said sound conduit.

19. A sound-amplifier comprising, walleparallel with said horn from near the outer arranged to form a diverging sound cham'- ber open at its front or larger end, a horn supported lengthwise within said chamber, a

.sound conduit at the inner ends of said horn and chamber, a sound-conveying tube mount; 'l0 ed outside of -said chamber so as to extend from the front toward the rear thereof, the outer end of-said tube being vadapted to be connected with a source of soundand the inner end of said tube bein connected to said sound-conduit, and an adjustable-valve for controlling. the relative proportion of sound waves issuing simultaneously out of said chamber and said horn.

20. A sound-amplifier comprising a box or l0 cabinet having an outer opening at the front, walls arranged in said cabinet to form a sound chamber diverging toward said outer opening, a horn supported lengthwise within said chamber and having sound openT U ingsy for laterally communicatin with said v chamber, a sound-conveying tu mounted in said cabinet outside ofl said sound chamberand extending from near said front opening toward the rear of the cabinet, the outer end of said tube being adapted to be con-v nected with a sound-producing device from outside the cabinet, means for connecting the inner end of said tube with the inner end of said horn, an open frame or rille secured over said outer opening o the cabinet, and an adjustable valve or 4shutter carried by said frame over the mouth of said horn to control the relative proportion of sound waves issuing out of said chamber and said horn.

21. A vsound-amplifier comprisin walls arranged to formadiverging sound c amber open at its front or larger end, a horn supported lengthwise within said chamber, a sound conduit at the inner ends of said horn and chamber, and a sound-conveying tube mounted outside of Said chamber, said tube i compris' a section extending substantially lne ope of said chamberV toward the rear thereo and a second section extending transversely of said horn at the rear of said chamber' for connection with said sound conduit, the outer end of said tube being adapted to'be connected with a source of sound. A

22. A sound-amplifier comprisin walls arranged to form a diverging soung chamber open at its front or' larger end, a horn supported lengthwise within'saidchamber and terminating substantially at the mouth y of said chamber, said horn having sound openings for laterally communicating withv Said chamber, a tapering sound-conveyi tube mounted outside of said chamberv v and a substantiall parallel with and i laterally of said horn,t e smaller end of said tube being ada ted to receive or be con# substantially U-shaped lllv connecting the larger end of said tube with the inner end of said horn.

23. A sound-amplifier comprising a box or cabinet with an outer opening, walls arranged Within said cabinet to form a sound chamber diverging toward said outer Aopening and termlnating substantially at said opening, a horn supported lengthwise Within said chamber and terminating substantially at the mouth of Said chamber, 'said horn having sound openings for laterally communicating with said chamber, a tapering sound-conveying tube mounted in said cabi-l net outside of said sound chamber and ar ranged substantially parallel with and laterally of said horn, the smaller end of said tube being adapted to receive or be connected with asound-producing device from outside the cabinet, a substantially U-shaped tubular member for connecting the larger' lend of said tube with the inner end of said ihorn, and a udevice for vcontrollihg the proportion of sound Waves issuing simultaneously through said lateral openings and -through the mouth ot the inner horn.

y Certicate certied that` in Letters e application of Adolph lt is vherab i924, upon t improvement in Sound Ampliers, an tion requiring correct-ion as follows: Page and that Maese comprising a tubular section open at bothends for the passage of sound, and an outwardly flaring flange around said tubular section and'radially 'spaced therefrom, said Harige being adapted to support the inner end of the outer horn and one'end of said tubular section being adapted to support the inner end of the inner horn.

426. A. sound-amplifier comprising a pair of nested diverging sound chambers, the Walls of one of said chambers being of a material adapted to give a resonant reproduction and the Walls of the other chamber bein of a material adapted to give a relatively soter or more mellow reproduction, yand means for controlling the relative proportion of sound Waves issuing'simultaneously out of said chambers. v

27. A sound amplifier comprising walls arranged to form a diverging casing, a Wall mounted Within said casing to divide the same into two outwardly diverging sound chambers of diierent tonal characteristics, said chambers being open at the larger outer ends for the emission of sound, means for connecting 'the inner ends of said chambers 'with a source of sound, and means for con# trolling the relative proportion 'of soundv Waves passing simultaneously through said chambers.

AnoLPn A. roms,

ot orrectiou.

A.. Thomas, of, New

error yappears' in the printed specica- 5., after line 122 insert the words 'aduce the said LettersfPatent should e read with this correction therein that the samemay conform to the, record o the case in the Patent @ce Signed and sealed this 5th [einen] any er august, an. i.

Y A... Hunan* t Acting Umnmeaz'oaer of Patente,

ork, N, Y., for an 

